When Life Gives You Excrement, Make Fuel?

Via Ezra Klein, The New Scientist observes that “A kilogram of beef is responsible for more greenhouse gas emissions and other pollution than driving for 3 hours while leaving all the lights on back home.”
People tend not to understand this very well because the tendency is to use the term “carbon dioxide” as a shorthand for “greenhouse gasses.” But though CO2 is the most common greenhouse gas, it’s far from the most potent. And livestock create huge amounts of methane both from their farts (yes, really, this is a real problem) and from the decomposition of their manure. The good news, as the good people at the Danish Biogass Association were eager to explain to me yesterday, is that there’s a way to deal with the manure side of this. Methane, in addition to being terrible for the environment when released directly into the air, is also usable as fuel (”natural gas”) and when used as fuel it’s relatively clean-burning compared to coal or oil. What they do at biogas plants is basically gather up a huge stinking pile of shit which is submitted to anaerobic digestion. This leaves you with, on the one hand, some digested manure that can be used as an effective and non-emissions-producing fertilizer and on the other hand some methane gas you can use to heat homes or generate electricity.
The biogas itself involves some CO2 emissions, so this isn’t a perfectly green technology. But making the biogas is much cleaner than not making the biogas if we assume that the quantity of animal excrement produced is independent of the existence of the biogas facilities. In other words, if the demand for meat is determining the quantity of cow and pig shit, then biogas plants count as very clean. They sharply reduce the quantity of methane put into the air, and can substitute for other dirtier fuels like coal or oil. If biogas were to actually become such big business that people started raising pigs specifically for the purpose of turning their shit into home heating fuel, then that wouldn’t work ecologically at all.
Currently, though, biogas requires substantial subsidy (in the form of a feed-in tariff) to be viable. So the smart green move is to subsidize biogas production enough to clean up the excrement we have, but not so much as to encourage the creation of additional livestock. In principle, it would probably make sense to have some kind of tax on meat that could be used to raise revenue to defray the cost of biogas subsidies.

Related

Everyone loves natural gas these days, and why not? It’s cheap, there’s plenty of it, it’s cleaner than coal and it can be used instead of petroleum to power cars and trucks.
But natural gas drilled out of the ground, otherwise known as fossil methane, isn’t the only gas in the market.
Biogas, the non-fossil-based methane generated by trash landfills and wastewater treatment plants, is attracting increasing attention, and it’s easy to see why.

Methane is one of the worst greenhouse gases. Whilst not as abundant as carbon dioxide, and therefore not quite as well publicised, it is actually 24 times as affective as CO2 at trapping heat in the atmosphere.Methane is also abundant in farts, especially from grazing animals such as cows.

Yesterday, carbon dioxide levels in Earth's atmosphere reached a major milestone: a daily average above 400 parts per million. The new high — the highest in human history — was recorded at two separate stations — one in Hawaii and the other in San Diego, California.

“Sometimes, we get a little parochial in Canada — we think that the whole world is entirely focused on tar sands as the biggest problem. What we’re saying here is that it’s one of the biggest problems.”
Canada’s oil sands are midway down the pack of the world’s climate change villains, according to a new Greenpeace report ranking potential carbon emissions from the globe’s top energy developments.

Canada’s response to President Barack Obama’s challenge to reduce emissions of global-warming gases from the oil sands starts with sewage and algae.
The paste-like crude extracted from oil sands is softened by heat and steam to make it flow though pipelines. Burning natural gas to process the fuel creates carbon dioxide that researchers say can be mixed with waste water and fed to algae, which can be processed into cattle feed and other products.

“Once people hear that the economics are very good, maybe we won’t have everybody dash to gas and throw out coal. We hope the rest of the world can learn from our plant.”
A technology that holds the hope for cleaner use of coal will be tested on a commercial scale for the first time in Canada next year, aiming to resolve big uncertainties about the vast amount of power it will need.